This invention relates to an improved means for actuating a balancer of an engine.
Generally, in an engine having a secondary balancer, it is necessary to rotate one of two balancer shafts positioned on opposite sides of a crankshaft in a reverse direction relative to the rotational direction of the crankshaft. To this end, it is necessary to provide special reversing mechanism for said one balancer shaft. The reversing mechanism includes a gear provided on one balancer shaft and an idle gear mounted on an idle gear shaft which is actuated through a sprocket provided thereon and a chain by the crankshaft.
Also, in a balancer in which a pair of balancer shafts rotate in the same direction relative to the rotational direction of the crankshaft, it is necessary to provide pullys, gears and sprockets on said balancer shafts and crank shaft to rotate the balancer shafts. In both cases, there are disadvantages that the entire construction of the engine is large and the cost thereof is high.
An oil pump used for supplying lubricant to the engine is actuated through an oil pump gear and an oil pump drive shaft which are provided on a cam shaft or crankshaft. The oil pump drive shaft is connected by a coupling to a drive gear shaft of the oil pump to actuate the latter. However, in long period of use, the coupling wears and has an undesirable play to cause it impacts or vibrations. In this result, discrepancies of clearance or wear arise between the drive gear shaft and a drive gear securely fitted thereon by a bush, at the engaging portions of the drive and driven gears and between said gears and a casing of the oil pump, thereby causing lack of the desired output pressure.